re: public speaking: There are in person groups like Toastmasters. Alternately, you can record yourself speaking about something and try to give yourself a self-critique.
Here’s an exercise I’ve run before: Person 1 picks a word at random; Person 2 immediately starting speaking about something relevant. At 15 second intervals for 1-2 minutes, Person 1 throws out new words; Person 2 needs to keep speaking about the new words, and to flow smoothly between topics. (You can substitute Wikipedia’s random article button for Person 1.)